There have been some conventional optical connectors, described in Japanese Patent Publications Kokai Showa 57-74714, Kokai Showa 59-125706, Kokai Showa 62-7009, Kokai Showa 62-138805, Kokai Showa 62-205303 and Kokai Heisei 3-25405 and a Utility Model Publication Kokai Showa 63-78906.
According to one of the above mentioned conventional optical connectors, a ferrule has a flange with projections and a housing has grooves to be engaged with the projections of the ferrule so that the ferrule and the housing are aligned to each other in assembly. Although, the grooves and the projections are required to be precisely adjusted in position with the hands of a user, it is difficult to get precise adjustment of them, because it is hard to look at the inside of the housing. Therefore, the eccentric direction of an optical fiber may be deviated from the key of the housing, and whereby the optical connector itself may be mis-assembled.